U.S. Pat. No. 4,727,767 (issued Mar. 1, 1988 to AiKi et aL), U.S. Pat. No. 4,876,917 (issued Oct. 31, 1989 to Aiki et al.), and JP-B 2-35080 U (published Sep. 21, 1990) disclose a torque transmitting and torsion damping apparatus. This known apparatus employs a friction clutch called hysteresis mechanism, which generates friction during relative rotation between a first inertia body including a driving plate and a second inertia body including a flywheel. In the known friction clutch, a pressure plate called hysteresis plate is provided with a bent portion fitted into a bore formed in the driving plate and a cone or Belleville spring acts on the pressure plate. The pressure plate can move in an axial direction along an axis of rotation of the first inertia body since the bent portion can slide relative to the bore. The pressure plate requires bending process to form the bent portion, thereby increasing manufacturing cost. The portion where the bent portion bears stress during relative rotation between the first and second inertia bodies changes when the pressure plate moves as the friction lining of the mechanism wears. This increases moment applied to the bent portion over the extended period of use with the friction lining unchanged. This causes mechanical failure of the bent portion of the pressure plate.
An object of the present invention is to provide a torque transmitting and torsion damping apparatus employing a pressure plate that has no bent portion for engagement with the adjacent inertia body.